what is rna polymerase

RNA polymerase is an enzyme responsible for copying a DNA sequence into an RNA sequence during the process of transcription. It is a complex molecule composed of protein subunits that controls the process of transcription, during which the information stored in a molecule of DNA is copied into a new molecule of messenger RNA. RNA polymerase is found in all living organisms and many viruses. Depending on the organism, RNA polymerase can be a protein complex or only consist of one subunit. Bacteria contain a single type of RNA polymerase, while eukaryotes contain three distinct types. RNA polymerase performs a plethora of chemical reactions and undergoes multiple conformational changes in order to accurately produce a full-length RNA copy of a gene.